Acoustic positioners, which use acoustic standing wave fields to hold, position or levitate, an object in a chamber away from the chamber walls, is especially useful in the microgravity environment of an outerspace vehicle. In such an environment, the small positioning force of an acoustic field is sufficient to hold the object in position. Under simple but unrealistic conditions, where a spherical object of any size lies in a spherical chamber, or a very small (compared to the chambers) spherical object lies in a chamber of simple geometric shape (which is either a rectangle, cylinder, or sphere), and the gas or other fluid in the chamber is of a uniform moderate temperature, formulas can be developed for estimating the equilibrium position of the object. However, it is difficult or impossible to predict the precise equilibrium position or restoring forces on the object in realistic situations where the conditions are complex, as where the chamber shape and the object shape, size and composition are arbitrary, and where there is a large temperature gradient in the fluid within the chamber. Furthermore, formulas are not available for predicting the orientation of nonspherical objects in a given acoustic standing wave field.
One important application of acoustic positioning is to enable melting of an object of high temperature-melting materials, (at least about 1500.degree. C.) while positioning the object away from the walls of a crucible that could contaminate the molten object. Since positioning forces are low, it is difficult to perform experiments in Earth gravity that will indicate the position and orientation of the molten object. Because of large temperature gradients in the gas within the chamber, it is difficult to determine the position and orientation of the molten object in a microgravity environment. A method and apparatus which enabled accurate prediction of the equilibrium and/or orientation of an acoustically positioned object in a microgravity, environment, as well as prediction of restoring forces and torques, during experimentation in a one G (Earth gravity) environment, would be of considerable value.